Two states have buffer zone laws besides Massachusetts, whose statute the US Supreme Court rejected – and those two look safe. But cities and towns also keep protesters at bay from abortion clinics, and some of those laws may not survive.

Boston — Cities and states across the US are scrambling to determine whether their laws regarding abortion clinic buffer zones are permissible, after the US Supreme Court ruled Thursday that a Massachusetts statute mandating a 35-foot protester-free zone at clinics is unconstitutional.

Some buffer zone laws are likely to pass legal muster, but others will almost certainly be struck down – a distinction, experts say, that’s literally a matter of feet and inches.

The high court’s decision Thursday was unanimous, finding that Massachusetts had violated the free-speech rights of anti-abortion activists seeking opportunities to talk clinic clients out of the procedure. But in spite of the unanimity, there were some signs of division. Four of the nine justices indicated that they see buffer zones in general as colliding with free speech, while the other five indicated that the Massachusetts law was merely overbroad.

That distinction is what has other states and cities with buffer zone laws wondering if theirs are OK, and for how long. A small shift of opinion by just one justice, experts say, could change everything.

“We’re talking about a case that is in some ways a 5-to-4 decision,” Jonathan Entin, a professor of law and political science at Case Western Reserve University, says of the McCullen v. Coakley ruling. “So, might some member of the five-justice majority be persuaded that buffer zones in general are problematic? I don’t know. That’s the question.”

The early analysis is that Colorado's buffer zone law is safe. It establishes a "floating buffer" – after anti-abortion activists come within 100 feet of a clinic, they must not approach within eight feet of someone entering the facility. The US Supreme Court upheld that approach, in 2000.

Several cities and states, including Massachusetts, had originally modeled their own buffer zones after the Colorado law. But the Massachusetts legislature, among other state and local governments, opted in 2007 for a simpler fixed line, after police complained that the floating provision was difficult to enforce.

Besides Massachusetts and Colorado, only Montana has a statewide buffer zone law. Its statute is in many respects a less-restrictive version of Colorado’s.

“I definitely think that’s likely to stay,” said Mr. Entin.

But several cities and towns rely on fixed buffer zones like the repudiated one in Massachusetts, and for them the McCullen v. Coakley decision is creating more uncertainty.

Perhaps nowhere are local buffer regulations on shakier ground than in Portland, Maine.

The city’s buffer law, which requires protesters to remain 39 feet from abortion clinics, was being litigated before Thursday's high court ruling. During oral arguments in federal district court there last week, Judge Nancy Torresen called the forthcoming Supreme Court decision “the elephant in the room,” according to the Portland Press Herald.

Rochester, N.Y., Buffalo, N.Y., Melbourne, Fla., and Pittsburgh, like Portland, all have fixed buffer laws on the books. But for a variety of reasons, these provisions are more likely to remain, experts say.

In the case of Melbourne, the US Supreme Court in 1994 upheld a law that mandated a 36-foot fixed buffer at one abortion clinic – in large part because the law is narrowly tailored to a specific location where severe harassment had regularly occurred, experts say.

“The Florida case was not a state law, but rather an injunction against what happened at one particular clinic,” says Entin. “I think we are talking about two separate issues.”

In 1997, the high court also upheld Buffalo's and Rochester’s 15-foot fixed buffers for similar reasons – citing the specificity of those cities’ laws.

Indeed, in Thursday's ruling, Chief Justice John Roberts noted the statewide scope in Massachusetts versus the “narrowly tailored” law in Buffalo.

In Pittsburgh, meanwhile, there's no consensus regarding the staying power of the city's buffer law.

“I would say there’s a pretty decent change that it will hold up,” says Steven Baicker-McKee, an assistant law professor at Duquesne University in Pittsburgh. “What the court seemed to focus on was, were there less-restrictive measures that the state could have taken up for safety…. In Pittsburgh, one of the things that the court did was calculate the sheer size of the zone of the barrier. You end up with a pretty big area, which didn’t give protesters much of an opportunity to speak out.”

Richard Fallon Jr., a professor at Harvard Law School in Cambridge, Mass., is less optimistic about the future of Pittsburgh's buffer zones, telling the Pittsburgh Post-Gazette that the high court’s ruling raises “serious questions,” though it isn’t a “slam dunk” for anti-abortion forces.

In Massachusetts, meanwhile, authorities pledged to act quickly to protect from harassment women entering the five abortion clinics in the state.

“We will utilize all of the tools we have available to protect everyone from harassment, threats, and physical obstruction,” said Attorney General Martha Coakley, in a statement. She added that her office will issue injunctions against protesters who resort to intimidation.